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Annex 12
As climatic changes could increase physiological stress on cultured stock this would not only affect productivity but also increase vulnerability to diseases, in turn imposing higher risks and reducing returns to farmers. Interactions between fisheries and aquaculture sub-sector could create other impacts, for example, extreme weather events resulting in escapes of farmed stocks and contributing to potential reductions in genetic diversity of the wild stock affecting biodiversity more widely. Climate change is a compounding threat to the sustainability and development of aquaculture.
The session on the sub-theme will discuss environmental monitoring of water and sediment quality associated with ponds, net cages, and pens to ensure productivity and sustainability as well as minimizing the adverse impacts of and adaptations to climate change. Research needs and strategic actions on aquaculture that will promote the environmental sustainability of the region in the next 10 years will be reviewed and finalized.
Issues
(i) Protecting the Environment
Excessive use of antibiotics and chemicals. Some chemicals and other anti-microbial agents that are used for human and animal health and welfare are now being used in aquaculture for the prevention, control or treatment of infections in farmed fish. Although it is recognized that some aquaculture operations are reliant to chemical usage and the continued access to these and other effective antimicrobial agents is important, the potential danger associated with misuse of these chemical inputs has led to widespread concern on food safety and environmental issues because residues of these chemical or their metabolites could eventually end up in aquaculture products and persist in the culture environment.
Abuse in the use of feeds and fertilizer. Nutrients from excess food and fertilizers from aquaculture operations can result in eutrophication of water bodies where there is significant aquaculture activity. There is increasing evidence from research that show that feed inputs can be reduced without negatively affecting production. In the case of striped catfish culture, it was shown that feeding to satiation once daily was a more efficient feed management technique compared to feeding to satiation twice daily which was the “traditional”
practice. This refined feeding strategy has been adopted by farmers resulting in better economic returns as well as reduced effluents released by farms into the environment. In tilapia culture in ponds, feed inputs can be reduced by either delaying the onset of supplemental feeding, feeding on alternate days or sub-satiation feeding without compromising growth, survival and production. Production of tilapia grown in cages in lakes and fed on alternate days was also found to be comparable with production in stocks that were fed daily.
Similar results were likewise obtained for milkfish grown in brackishwater ponds. Significantly improvements in overall farm productivity can be achieved without necessarily increasing the cost of production by improving FCRs through regulation of rations and optimizing feeding frequency, duration and timing.
The use of quality feeds along with proper feeding management is important for sustainable aquaculture development. Poor feed utilization and resulting in high Feed Conversion Ratios (FCRs) can be brought about by inappropriate selection of feed type (pellet type, size and formulation), quality and feeding strategy. In turn, the quality of the feed is determined by the quality and digestibility of feed ingredients that were used, the suitability of the formulations in terms of supplying the nutritional requirements of the cultured species, stability of feed in the water, storage conditions and handling of the feeds, and manner of feed preparation (extruded or pelleted). Because fish meal, which is the main protein source in aquaculture feed is becoming increasingly expensive and limiting, feed ingredients that could potentially be used as replacement for fish meal in farmed fish feed has been actively sought for many years. In the same vein, culture of species which require low levels of fish meal in their diets (e.g. tilapia, carps, milkfish, rabbitfish and others) is being promoted.
In Integrated Multi-Trophic Aquaculture systems (IMTA), various organisms having different feeding niches are grown together in one system by combining, in appropriate proportions, the cultivation of fed aquaculture species (e.g. fish or shrimp) with inorganic extractive aquaculture species (e.g. seaweeds), organic extractive aquaculture species (e.g. oysters or mussels) and benthic invertebrates (e.g. holothurians, gastropods and aquatic worms) that will feed on uneaten feeds and fecal matter that will accumulate in the sediments of fish ponds or at the bottom of fish pens or fish cages. The aim of IMTA is to increase profitability per cultivation unit as the wastes of one crop (fed species) are converted into fertilizer, food and energy for the other crops (extractive aquatic species), which can in turn be marketed for additional income.
Through IMTA, some of the food, nutrients and energy considered lost and polluting in monoculture systems are recaptured and converted into crops of commercial value, while natural bio-mitigation takes place. In this set up, all components in the culture system have an economic value and play key roles in the recycling
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processes of the system. Thus, IMTA represents a balanced ecosystem management approach to aquaculture for environmental sustainability, economic stability through improved output, lower production cost, product diversification and risk reduction, and societal acceptability through better management practices.
Need for better management of the aquaculture sector. The concept of environmental capacity can be used as a strategy to alleviate, if not prevent coastal pollution brought about by intensification of aquaculture activities. For example, based on hydrologic features of the area and trends established through regular monitoring of water and sediment quality parameters, local ordinances can be passed to set limits to the area and/or numbers of pens or cages that can operate in a certain mariculture areas. This can further serve a basis for the issuance of permits to set up structures and operate fish farms. This however, will call for effective monitoring and enforcement of regulations to ensure that the carrying capacity of the environment is not exceeded and activities are carried out in an environment-friendly manner.
Environmental imbalance due to destruction of mangrove and depletion of fish population/loss of biodiversity. Mangrove areas are known for their important function as nursery grounds for various species of marine organisms as well as their protective function against storm surges. Conservation of remaining mangrove areas and rehabilitation of mangrove forests are being promoted not only to serve as buffer zones for expected increased storm surges with the increase in sea levels due to global warming but also to restore nursery grounds for aquatic species and arrest the loss of biodiversity.
(ii) Adapting to Climate Change
Tropical sea surface temperature records from the major ocean basins showed a temperature increase of 1-3oC over the past 3.5 million years. Sea surface temperature across much of the tropics has increased by 0.4-1oC since the mid-1970s. Even though warming in the tropics is projected to be relatively small compared with high-latitude regions, tropical animals may bear disproportionally larger impacts of increasing temperatures in their habitats because tropical organisms have narrower thermal tolerance ranges than higher- latitude animals; they also live in temperature ranges closer to their physiological tolerance threshold.
Therefore, even small increases in ambient temperature may be critical for some species. The most well known example is probably coral bleaching caused by a few week’s thermal anomalies of only 1-2 °C. Thus, aquaculture production in the Southeast Asia may be significantly affected by warming in the area through negative impacts on early development and recruitment of aquatic organisms. Higher temperatures may also increase physiological stress to the cultured stocks thereby making them more susceptible to diseases.
Likewise, increases in temperature will also lead to ocean acidification and will impact on calcareous shell forming organisms.
Acidification may also pose another significant threat to aquaculture (and catch fisheries). Since the oceans serve as a natural carbon sink to the CO2 gas and other greenhouse gases that are released into the atmosphere, this has caused the decrease in ocean surface pH and it is predicted that by the end of the century (2100), ocean pH will decrease by 0.3-0.5 units from the present level. These changes will affect biological calcification rates and have had negative effects on various marine organisms including calcifying plankton, mollusks, coralline algae, and reef-building corals which are particularly essential for a lot of marine organisms for growth, reproduction and as nursery grounds.
Increases in the frequency and intensity of extreme weather phenomena such as storms, prolonged droughts or longer than usual rainy season are predicted and are already being felt or experienced. Changes in weather and climatic patterns could potentially disrupt reproductive cycles of aquatic organisms thereby affecting recruitment and availability of wild seeds used for aquaculture. In the same manner, reproductive cycle of captive breeders could also be disrupted thereby further compromising seed supply.
Extreme weather events like typhoons and flooding and storm surges associated with these weather disturbances can affect aquaculture operations and result in destruction of culture facilities, loss of stocks and consequent production losses. Mass escape of stocks resulting from destruction of culture facilities also poses potential threat to biodiversity. Coastal communities and low-lying inland areas would be especially vulnerable.
Compared to other animal production systems, the carbon footprint of aquaculture is much lower because most of the production is from freshwater herbivorous or omnivorous species such as carp that are dependent on primary productivity or low levels of supplementary feeding. However, some species (e.g.
shrimp, salmon and high value marine carnivorous fish) have both high feed energy and system energy
demands and thus high carbon footprints. For some developing countries including those in Southeast Asia, aquaculture production is focused on high value aquaculture species aimed primarily for export.
Identification of research needs and effective implementation of strategies that could help the region’s aquaculture sector/fish farming communities adapt better to climate change are major challenges of the region
Recommendations
(i) Protecting the environment
Increasing the pressures on natural resources, such as water and habitats, and awareness of the importance of improving environmental management in ASEAN, will continue to drive the aquaculture sectors towards reduction of the impacts of aquaculture on the environment, and making more efficient use of natural resources for aquaculture.
Whilst there has been significant improvements and move towards more responsible use of antibiotics and chemicals in aquaculture, continued and stringent monitoring and control is still needed to reduce the unnecessary and irresponsible use of such chemicals and drugs in aquaculture. To address food safety issues, an accurate inventory of chemicals and drugs used in aquaculture operations is needed. Data on withdrawal periods for antibiotics and other chemicals commonly used in aquaculture are likewise necessary in order to establish guidelines on the production of safe aquaculture products.
Improve the management of the aquaculture sector. The concept of environmental capacity can be used as a strategy to alleviate, if not prevent aquatic pollution brought about by intensification of aquaculture activities. Local ordinances can be passed to set limits to the area and/or numbers of pens or cages that can operate in a certain aquaculture area. This can further serve a basis for the issuance of permits to set up structures and operate fish farms. Zoning regulations should also be in place to ensure that there is no over- development of aquaculture in certain areas. These however, will call for effective monitoring and enforcement of regulations to ensure that the carrying capacity of the environment is not exceeded and activities are carried out in an environment-friendly manner.
Following is an operational scheme where an aquaculture facility is allowed some period of rest.
Breaks in aquaculture production are important in that it allows the immediate aquaculture environment to recover from environmental stressors. For example, monitoring of water and sediment quality parameters reveal that levels of nutrients are high during the culture period but tend to decrease during the fallow period.
Fallowing is also an important strategy in breaking infection and re-infection cycles.
There should be wider and more intensified information dissemination with regards to feeding management schemes that could reduce the environment impacts of aquaculture without negatively affecting production efficiency. The following are primary issues that currently constrain feed use and management in aquaculture: 1) limited access to information on feed and feed ingredients (availability, prices and quality), 2) poor feed preparation, processing, handling and storage at the farm level, 3) inadequate monitoring of feed and farm performances, 4) low impact of current dissemination strategies on improved feeding and feed management, 5) gaps in the understanding in the economic aspects of feed management, 6) health aspects and their implications on feed management, and 7) lack of regulatory mechanisms for feed quality.
Various culture technologies that integrate aquaculture with the environment have been developed (e.g. aqua-silviculture, poly-culture, closed or re-circulating systems, etc). Recently, the concept of integrated multitrophic aquaculture (IMTA) systems that combine aquaculture species (finfish or mollusc) which are fed artificial or natural diets, and suspension extractive species like mussels or oysters (organic extractive) and seaweeds (inorganic extractive) or deposit extractive species like sea cucumbers or sea urchins has become quite popular. This culture system has the unique characteristic of reducing the negative impacts of aquaculture on the surrounding environment while increasing the profitability of an aquaculture operation by having multiple crops instead of just one. IMTA therefore promotes economic and environmental sustainability.
The aquatic environment offers enormously rich resources; hence, it is crucial that activities are directed towards achieving a balance between aquaculture development and protection of the environment and aquatic biodiversity. Mangrove conservation and rehabilitation are being promoted in recognition of the important function of mangroves as nursery grounds for myriad species, as well as their protective function.
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On the other hand, selection of sites for mariculture should ensure that potential negative impact of aquaculture activities on nearby sensitive ecosystems such as coral reefs, seagrass beds are minimized if not totally avoided.
Several guidelines are in place to ensure that aquaculture development is undertaken in a sustainable and environment-friendly manner including the Regional Guidelines for Responsible Fisheries in Southeast Asia-Responsible Aquaculture. Several other codes of conduct/practice, best management practices (BMPs), Good Management Practices (GMPs) for the culture of specific economically important commodities have been formulated. These, along with certification schemes are important for increasing public and consumer confidence in aquaculture production practices and products and are widely recognized by international organizations and many non-governmental bodies.
(ii) Adapting to Climate Change
Mitigating the impacts
Selection of some strains that are better adapted to warming and acidification will be an important adaptation measure. Some animals, including fish, show thermal plasticity and can adapt to higher than usual temperatures suggesting the possibility of successfully establishing thermal-tolerant aquaculture animals through selective breeding.
Some freshwater animals, particularly those inhabiting stagnant lakes and ponds, are probably less affected by high CO2, because these water bodies usually have high CO2 levels. Dissolved oxygen concentrations in these water bodies will also likely be low, hence the culture of air-breathing fish species such as Anabas spp., Boleophthalmus spp., Channa spp., Clarias spp., Monopterus spp., and Sccobranchus spp. which are already cultured in southeast Asia should be promoted further.
Early developmental stages of most organisms seem particularly vulnerable to temperature rises and acidification. Thus, it is most essential to raise embryos and larvae under conditions favorable for their development. To reduce impacts of acidification, excess CO2 in air supply could be absorbed into an alkaline solution before being delivered to rearing tanks. Some alkalizing agents such as soda lime could be directly added to rearing water, but their biological toxicity must be carefully tested before application. If possible, larval rearing should better be conducted under favorable temperature conditions. Once larvae have grown up to a stage that is more tolerant to environmental stress, they could be transferred to usual aquaculture grounds.
This might be applicable to bivalves such as clams, mussels and oysters, and crustacean species.
Define strategies for mitigating greenhouse gas emissions from aquaculture (for instance, finding alternative energy sources). The use of algae/seaweeds as bio-fuel could be an area of study.
Review energy consumption (i.e. taking into consideration the life cycle approach) in aquaculture and greenhouse gas emissions associated with direct energy inputs for aquaculture systems, covering farm sitting and operations, and value chains.
Adaptation Measures
Aquaculture can also be an adaptation solution, for example as a livelihood option for agriculture farmers in coastal areas affected by saline intrusion due to sea-level rise, for water storage in drought affected regions.
The following were also identified as adaptation techniques that could be taken by the Member countries and the fish farming communities:
Mapping of sites that are vulnerable to effects of climate change. Identify areas or sites that are vulnerable to effects of climate change. This also involves mapping or assessing the vulnerability of aquaculture dependent communities to climate change.
Research areas for climate change adaptation. Conduct studies on areas of aquaculture that would lead to identification and promotion of aquaculture species, strains, farming systems and techniques that will adapt better to climate change.
Investments on infrastructures/habitat. Assess and improve the existing infrastructures/habitat to ensure safety of coastal fish farming and fishing communities and enhance their adaptive capacity to climate change. The following measures were suggested:
Invest on infrastructures such as early warning systems and other safety measures.
Restore and maintain mangrove forests as a strategy to reduce greenhouse gas emissions and provide the first line of defense during flooding and possible erosion.
National plans for climate change adaptation. Strategy that aims to avert the impacts of climate change in the Member Countries must be put in place. This also includes ensuring that the needs of aquaculture and fisheries are incorporated into the government’s plans for climate change adaptation and that these sectors are involved in the planning, development and implementation of activities that pertain to climate change.
Awareness building. The participants noted that aquaculture and fisheries attract little attention in the bigger fora/initiatives on climate change. For instance, these are barely mentioned in the report of the Inter-Governmental Panel on Climate Change (IPCC). The recommendations were for the aquaculture/fisheries sectors to raise ‘voice’, be visible and get engaged in the bigger fora and initiatives on climate change. Such actions are important to ensure that aquaculture and fisheries are accorded due attention in climate change initiatives and also, so that resources can be directed to these sectors to help the people adapt to climate change.
Institutional strengthening. Institutional strengthening must be pursued to increase the resilience and overall capacity of various stakeholder groups on aquaculture (including farmers) and to enable them to adapt to the challenges of climate change. Empowering various stakeholder groups through capacity building and knowledge transfer were identified as key elements that could strengthen these stakeholders.
Improve cooperation within the aquaculture sector and with other sectors. Institutional cooperation or institutions working together at all levels is of utmost importance to effectively address issues on climate change. One issue within the aquaculture sector that has become more challenging in light of the impacts created by climate change (e.g. drought) is the multiple use/demands on water. The participants noted that in view of the increasing demands for water for human use, the more integrated approaches within the sector and between sectors and the promotion of these approaches are needed.